First, a single set of DNA standards is used to generate up to three standard curves using three different primer pairs that amplify targets of 41 bp, 129 bp, or 305 bp within a conserved, single-copy human locus. Next, the 41 bp assay is used for absolute quantification of DNA samples. For assessing DNA quality, standard curves are generated and samples assayed with the 129 bp and/or 305 bp primer premix(es). Since poor DNA quality has a greater impact on the amplification of longer targets, the relative quality of a DNA sample can be inferred by normalizing the concentration obtained using the 129 bp or 305 bp assay against the concentration obtained from the 41 bp assay. This normalization generates a Q-ratio (with a value between 0 and 1) that is indicative of DNA quality, or the amount of amplifiable material in a DNA sample.